The increased use of smartphones and other mobile devices using internet applications, video calls and e-mail is driving an unprecedented increase in world-wide wireless network traffic. From a Network operator's perspective, the key factors in driving wireless network topologies are their ability to meet demands for bandwidth, user capabilities as well as quality of service, QoS. Achieving the required capacities and fulfilling the quality of service, QoS, requirements depend on multiple factors, such as proximity of the users relative to the base station of the transceivers, the numbers of users in a cell, data throughputs and patterns as well as core network capabilities.
In conventional cellular networks macrosites can be installed on e.g. roof tops or at designated cell sites that typically have the base band units with the transceivers and RF power amplifiers in a cabinet enclosure while the antenna resides for instance on a tower mast. In such a conventional network the cabinet can be connected using a coaxial cable to the antenna on the antenna mast. This is the most common cell site approach for mobile cellular networks.
In LTE (Long Term Evolution) networks or LTE-A (Long Term Evolution Advanced) networks, the network architecture is transformed by the introduction of remote radio heads, RRH, which can be connected to a base station BS via fiber optic cables. The network can employ macro or micro base stations, the same as a traditional cellular site, but instead of having a conventional tall antenna mast, fiber optic cables can be used to distribute the base station signals for a group of antennas placed remotely in outdoor or indoor locations where required.
A common public radio interface, CPRI, forms a protocol interface between a radio equipment control, REC, and a radio equipment, RE, in a wireless network. The station is in a conventional wireless network located adjacent to the antenna in a small cabinet at the base of the antenna tower. Finding suitable sites can be a challenge because of the footprint required for the cabinet, a possible need for structural reinforcement of roof tops as well the availability of primary and back-up power sources. The common public radio interface, CPRI interface, allows the use of a distributed architecture where base stations containing the radio equipment control REC can be connected to remote radio heads RRH via wireless fiber links that carry the CPRI data. This architecture makes it possible that the remote radio heads RRH containing the radio equipment RE can be situated in environmentally challenging locations. The base stations containing the radio equipment control REC can be located centrally in less challenging locations where footprint, climate and power availability can be managed more easily. The CPRI data is transmitted in a downlink DL by the base station to the radio equipment RE and received in an uplink UL by the base station from the radio equipment RE.
The CPRI has been developed to aim for the radio interface standard of WCDMA (wideband code division multiple access) of UMTS (universal mobile communication system). Accordingly, using CPRI interface for public land mobile networks e.g. LTE/LTE-A having a signal organization structure different form the radio interface standard of WCDMA or UMTS poses problems in signal processing, in particular in case the signal processing should be performed on a predefined record of signal data out of a serial data stream with unknown data record boundaries, at first. For instance, the signal processing of LTE/LTE-A signals has to be performed on the set of IQ data representing a complete OFDMA signal. However, the IQ data relating to a complete OFDMA signal is not identifiable from the data stream framed to be transmitted through a CPRI link.